#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const int N = 15;
double f[N][N][N][N][5][5];
int a, b, c, d;
int main() {
    memset(f, -1, sizeof f);
    cin >> a >> b >> c >> d;

    for (int i = 13; i >= 0; i--)
        for (int j = 13; j >= 0; j--)
            for (int k = 13; k >= 0; k--)
                for (int w = 13; w >= 0; w--)
                    for (int x = 4; x >= 0; x--)
                        for (int y = 4; y >= 0; y--) {
                            double &v = f[i][j][k][w][x][y];
                            if (i + (x == 1) + (y == 1) >= a && j + (x == 2) + (y == 2) >= b
                                && k + (x == 3) + (y == 3) >= c && w + (x == 4) + (y == 4) >= d) {
                                v = 0;
                                continue;
                            }

                            v = 1;
                            int sum = i + j + k + w + (x != 0) + (y != 0);
                            if (i < 13) v += f[i + 1][j][k][w][x][y] * (13 - i) / (54 - sum);
                            if (j < 13) v += f[i][j + 1][k][w][x][y] * (13 - j) / (54 - sum);
                            if (k < 13) v += f[i][j][k + 1][w][x][y] * (13 - k) / (54 - sum);
                            if (w < 13) v += f[i][j][k][w + 1][x][y] * (13 - w) / (54 - sum);
                            if (x == 0) {
                                double t = INF;
                                for (int u = 1; u <= 4; u++) t = min(t, f[i][j][k][w][u][y] / (54 - sum));
                                v += t;
                            }
                            if (y == 0) {
                                double t = INF;
                                for (int u = 1; u <= 4; u++) t = min(t, f[i][j][k][w][x][u] / (54 - sum));
                                v += t;
                            }
                        }

    if (f[0][0][0][0][0][0] > 54)
        printf("-1.000");
    else
        printf("%.3lf", f[0][0][0][0][0][0]);

    return 0;
}